1. Field
This disclosure relates generally to integrated circuits, and more specifically, to a comparator for synchronous rectification.
2. Related Art
In many circuit applications, DC to DC converters are used to convert an input DC voltage to an output DC voltage. A buck converter is a converter in which the output DC voltage is lower than the input DC voltage, and a boost converter is a converter in which the output DC voltage is greater than the input DC voltage. Buck and booster converters provide the output voltage by controlling current in an inductor controlled by two switches (typically a transistor and a diode). In the case of a buck or boost converter implementing synchronous rectification, diode is replaced by a second switch (typically, a second transistor). The use of a second switch rather than a diode allows for more efficient operation by avoiding the losses from the voltage drop across the diode.
In applications with highly variable loads, it is desirable to prevent reverse current in the inductor. Negative inductor current significantly reduces the efficiency of the converter. Therefore, a need exists for circuitry capable of sensing when the inductor current of a buck or boost converter reaches zero.